1. Field
The present invention relates to an apparatus and method for cleaning a semiconductor substrate such as wafers.
2. Related Art
In a step of cleaning a semiconductor substrate, water rinse is executed after a chemical treatment and thereafter, spin drying or isopropyl alcohol (IPA) drying is executed. In the spin drying, rinse water is thrown off by a centrifugal force and thereafter, water drops left on a surface of the semiconductor substrate is evaporated. The spin drying results in a problem that fine patterns formed on the semiconductor substrate are collapsed by a capillary force due to a surface tension of water left on a surface of the semiconductor substrate. The problem has become more evident with recent progress in structural refinement of semiconductor devices.
The foregoing problem can be overcome by employment of the IPA drying instead of the spin drying to some extent since IPA has a smaller surface tension that is substantially one third of the surface tension of water. For example, U.S. Pat. No. 6,001,191 discloses a drying apparatus which can improve throughput in the IPA drying. However, with further progress in the structural refinement, adverse influences the drying step has on refined patterns have been desired to be reduced in refined devices after 30-nanometer generation.